About Carbon Fibre

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What Is Carbon Fibre

Carbon Fiber Reinforced Plastic (CFRP) or commonly known as Carbon Fiber is made of different forms of building blocks such as weaves, braids, and yarns. The fiber is formed by a long chain of carbon atom forming a bond responsible for its tensile strength as well as its light weight property.

Carbon Fiber Reinforced Plastic (CFRP) is said to be one-third lighter than any metal and is six times stronger. During the process of creating carbon fiber composites, first they are like hair like strands that are woven and twisted together forming what is known as carbon fiber tow. The designated weight for each tow are 3k, 6k, and 12k. Each weight level contains equal number of carbon strands i.e. a 12k carbon fiber tow contains 12,000 strands of fiber.

Why Use Carbon Fibre?

Over the years, carbon fibre has won over manufacturers and consumers alike worldwide. It is a lightweight and durable alternative to metals, and has proven its performance in more than aerospace, military, and motorsport industries. Its popularity can be credited to many different factors, all of which have been established in real-world use over time. Here are five reasons why you one should seriously consider the use of carbon fibre:

Long life span, minimal maintenance

One of the greatest advantages that carbon fibre and other composite materials have over steel is its lightness to performance ratio. Stronger than steel, yet several times lighter, it neither rusts nor corrodes, so one is assured of having the fit and finish of the product when it was new — several years down the road. Because of this, little maintenance is required, which also impacts on operating and replacement costs.

Efficient

Because of its light weight, carbon fibre reduces energy use, be it in mechanisms or as borne weights in mechanized or structural assemblies. Apart from energy conservation, lightness also reduces wear and stress, resulting in components or mechanisms that should last longer.

Upgraded performance

Carbon fibre has changed the game for thousands of products today. Used in aircraft, automobiles, sports goods, houseware, prosthetics, and other equipment, it has become a reliable, if still costly, alternative to traditional high-end materials like steel alloys, titanium, and aluminium.

Increased safety factors 

Being lightweight, carbon fibre is safer to produce, as well easier to assemble to handle in actual use. As we have said, it very strength to weight ratio allows products to have an extra safety factor built in, without affecting weight or mass unduly.

Keeping up with the times 

Needless to say, the quality and performance of carbon fibre has drawn a lot of attention to itself, and letís face, being the new wonder material, both manufacturers and consumers would not want to be known as laggards in adopting the latest high-tech material.

 

Types of Carbon Fibre

From its very name, one can surmise that carbon fiber is made from special fibers, of which layers and orientations are designed into a part to create specific combinations of strength, weight, and stiffness. This almost infinite variety of composition is in contrast to metals which are limited to what the manufacturer has designed and is capable of.

Although the very basic ingredient is composed of tiny fibers from carbon atoms, the main manufacturers produce from these fibers strands called tows, from which carbon fiber fabrics are produced. Look at these carbon fiber fabrics and you will notice distinct patterns, which are known in the industry as weaves. The most common weaves are plain and twill weaves, which Superleggera sources from Toray, one of the leading aerospace and industrial suppliers in the world.

As its name implies, plain woven fabric will show a simple over-under pattern.

The strength property varies from one weave to another. A unidirectional weave has high tensile strength weaving towards the fiber but is equivalently weaker in the opposite direction. Plain weave, however, has equal distribution of strength especially since the fibers are woven across each other.

Choosing which weave to use will depend on the part being produced, and the specific combinations of strength, lightness, and even flexibility, that the part, or designer, needs.

Expert knowledge of in design and manufacturing are what Superleggera brings into the picture.

Plain Weave

Plain weave

Plain weave

 

Twill

twill weave

Twill Weave

Manufacturing Process

To start off, we should have a primer on the basics of what the material is, as a background to the topics that we will take up later as we progress. No use talking about PAN, polymers, resins, impact, and sustainability without this background.

Most raw material in carbon fibre production today is made from a material called polyacrylonitrile. It is a polymer which is repeatedly heat-cycled (up to 1300 degrees centigrade), resulting in changes to the composition of the material. This process results in a so-called precursor that is almost pure carbon in the form of graphite. Hence the term carbon fibre. This is a very simplified explanation, as the production of PAN involves many precision steps. Note that the final quality of the end product depends highly upon the initial properties of these called precursors.

Precursors are the raw materials that specialized factories like Toray, Hexcel, Zoltek, Cytec, SGL, Toho, and others use to produce the woven products, fabrics usually, that are more familiar to us. Hardly household names, but already, they are pillars of an industry that will propel us toward innovations in renewable energy, structural materials and other futuristic inventions. Space elevators anyone?

To form carbon fibre into the material familiar to us involves the following steps:

Spinning – the step where the graphite power is mixed with another plastic to for the polyacrylonitrile or PAN.

Stabilization – the conversion process where the chemical bonding of the molecules are change from a linear one to laddery-type bonding. This is basically a heating process where the fibers are heated to 300 degrees Celsius.

Carbonizing – the step which heats the previously heated fibers in a furnace at 1300 degrees. In this process, the furnace is evacuated of oxygen so that the fibers do not burn but instead form tightly bonded crystals.

Surface treatment – involves oxidizing the fibers so that resins and epoxies bond properly.

Sizing – a coating process that prepares the fibers for the winding or weaving process.

As we’ve seen, carbon fibre manufacturing is far removed from the processes traditional engineers are familiar with. These are the reasons why it is so expensive, and why there are concerted efforts to steamline and make these processes more affordable.